Without limiting the scope of the invention, its background is described in connection with downhole pressure sensing, as an example.
In the process of drilling, testing, completing or producing an oil and gas well, it is often useful to be able to measure the pressure at various locations of the well. For example, of particular interest is the pressure in the various production zones that are traversed by the well. Typically, this may be achieved by including a pressure transducer as a portion of a test string included in the pipe string.
Alternatively, attempts have been made to place a pressure transducer on the outside diameter of the tubing or pipe string. Attaching the pressure transducer to the outside of the pipe string typically utilizes a threaded engagement usually included some form of tapered pipe thread, such as a National Pipe Threads (NPT). Although these types of threads are often used in such applications, it has been found that the pressure differential across the threads in testing or other well operations often exceed the specified pressure rating of the threads which has resulted in inaccurate pressure readings due to leakage. Additionally, it has been found that using threaded connections often makes installation of the pressure transducer on the outside of the pipe string difficult.
A need has, therefore, arisen for an apparatus for obtaining downhole pressure readings from the outside of a pipe string that does not rely on a metal to metal seal to prevent leakage. A need has also arisen for such an apparatus that is simple and quick to install. Further, a need has arisen for such an apparatus that may obtain pressure reading from both inside and outside of the pipe string and that may be locked in place following installation in order to withstand the hostile downhole environment.